Mixed electronic and protonic conductor materials were prepared using BaCe0.8Y0.1M0.1O3-delta (BCYM) as the protonic conductive phase and Ce0.8Y0.1M0.1O2-delta (MYDC) as the electronic conductive phase (in reducing atmosphere), with M=Y, Yb, Er, Eu. Dense specimens of these ceramic/ceramic composite materials (cercers) were prepared by solid-state reactive sintering: all the precursors for BCYM and MYDC were mixed, pelletized, and fired without any pre-calcination step of the individual ceramic phases. The X-ray diffraction patterns revealed the presence of the two desired phases. The study of the lattice parameters showed that the Y and M co-dopants were fairly well distributed between the perovskite phase BCYM and the fluorite phase MYDC. This interesting discovery is of importance for the preparation of two-phase ceramic materials. In addition to the structural study, the samples were analyzed by scanning electron microscopy and were found to be free of any undesirable phases. The two ceramic phases could easily be distinguished using the back-scattered electron mode, with grains between 10 and 30 microns. Energy dispersive X-ray spectroscopy confirmed the distribution of the co-dopant between the two phases.